How did you jump that high..

It's a roblox bug where you can spin around and jump at the same time to get extra height.

I was too lazy to time it.

i tried that but its probably based on the avatar specs

my avatar(s) mostly dont and cant even jump across a single fence unless with somone i can jump on

It’s a the base avatar. It’s done by turning around and jumping, which makes you jump a few studs higher, putting you into climb mode on a fence, which allows you to jump again to leap the fence.

You could get patrol and drive under the fence so you immediately have a vehicle

true. but its not as fast.